One-sided plasma display panel

ABSTRACT

A thin glass sheet carries seats of spaced, parallel electrodes on opposite surfaces thereof and a gaseous atmosphere overlies one surface. Applying an alternating current voltage exceeding a critical value across selected electrodes of each set causes a gas discharge to take place on the surface carrying the gas at the area of selected electrode crossing with localized visible light output.

United States Patent Lay [ 51 Feb. 29, 1972 [54] ONE-SIDED PLASMADISPLAY PANEL 1 72] Inventor: Frank M. Lay, Kingston. N.Y.

[73] Arstsignec: lntemattamal Business Machines Corporation, Armonk, NY.

[22] Filed: June 9, 1970 [2]] Appl. No.: 44,845

[52] US. Cl. ..3l3/l09.5, 313/220, 315/169 R, 340/343 [51] Int. Cl..1-l0lj 61/30 [58] Field of Search ..313/108 B, 109.5, 220; 315/169 R,169 TV; 340/166 EL, 343, 344

[56] References Cited UNITED STATES PATENTS 2,972,707 2/1961 Wood..315/169X 3,499,l67 3/1970 Bakeretal .l ..3l3/220X 562,429 6/1896Skinner ..340/343 Primary Examiner-Raymond F. Hossfeld Attorney-Sughrue,Rothwell, Mion, Zinn & Macpeak ABSTRACT A thin glass sheet carries seatsof spaced, parallel electrodes on opposite surfaces thereof and agaseous atmosphere overlies one surface. Applying an alternating currentvoltage exceeding a critical value across selected electrodes of eachset causes a gas discharge to take place on the surface carrying the gasat the area of selected electrode crossing with localized visible lightoutput.

6 Claims, 2 Drawing Figures PATENTED I972 3,646,384

INVENTOR FRANK M. LAY

ag, il-Kane! M ATTORNEYS ONE-SIDED PLASMA DISPLAY PANEL BACKGROUND OFTHE INVENTION 1. Field of the Invention This invention relates to planardisplay panels and more particularly to a simplified, low-cost displaypanel which eliminates the need for uniformity in spacing or accurateregistration between panel components.

2. Description of the Prior Art Relatively thin, planar display panelsemploying a localized plasma effect have been manufactured in the past,in two forms. In one form, glass plates approximately 54; inch inthickness are separated by a gas filled gap about mils in width and thegap is maintained by thin glass spacers. The inner faces of the platescarry horizontal and vertical sets of transparent electrodes covered bya thin glass insulating layer. The intersections of these electrodesestablish the spots that form the displayed pattern. Alternatively,instead of using two spaced glass plates, a three layer glass sandwichmay be employed with holes in the middle layer through which thedischarge occurs, although, in all other respects, this arrangement issimilar to the first described plasma readout panels. The three layerpanel involves inherently a registration problem since the perforatedcenter plate or middle layer must have the perforations accuratelyaligned with the points of intersection between the transparentelectrodes carried by the outer plates. With the two layer panel, thereis inherently a uniformity problem since it is hard to maintain auniform gas chamber of the order of several mils over the completesurface ofa large panel.

SUMMARY OF THE INVENTION The present invention provides a practicalsolution involving a single layer approach which solves both theregistration and uniformity problems. The present invention is directedto a flat panel constructed from a single thin sheet of insulatedmaterial with sets of spaced parallel electrodes positioned on oppositesides of the insulator sheet with one set orthogonal to the other. Theinvention makes use of a gaseous atmosphere applied to one of thesurfaces and by raising an alternating current voltage above apredetermined value, a localized gas discharge takes place on thesurface subjected to the gas, with localized visible light output.

Preferably a neon atmosphere at 200 torr. is maintained on one side ofthe glass sheet, confined by a clear glass cover with the matrixelectrodes constituting three lines per inch. A 500 volt, peak-to-peakfiring voltage is selectively applied to given row and column electrodesto effect bistable action. A thin insulation layer may overlie theelectrodes exposed to the gases.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective viewof a prior art three layer plasma display panel;

FIG. 2 is a perspective view, partially broken away, of the preferredembodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Prior to referring to FIG. 2illustrating one embodiment of the present invention, reference to FIG.1 illustrates a prior art plasma display panel 1, constituting a matrixdisplay formed as a sandwich of three thin plates 2, 3, and 4. Thecenter plate 3 is honeycombed with either etched or ultrasonicallydrilled holes 5. Transparent, thin film electrodes 6 and 7 are depositedon the outer surfaces of the two outer plates 2 and 4. The panel isevacuated and the array is filled with a mixture of neon-nitrogen gas orthe like. The application of coincident voltages of appropriatemagnitude to selected crossed grids, that is, electrodes 6 and 7, allowselected display elements to be ignited. Voltages applied to the crossedelectrodes are coupled capacitively into the cell so that only ACexcitation voltages are required. Display is seen through one set ofhighly transparent electrodes either 6 or 7, and the gas discharge isconfined totally to the cylindrical cavity formed by the three glasssheets 2, 3, and 4. However, since the display panels can bemanufactured such that approximately 18,000 tiny spots may be providedwithin a 4 inch square area, registration of the three plates isextremely critical. In addition, the manufacture of such display panelshas been relatively expensive.

Referring to FIG. 2, the gas discharge display panel 10 of the presentinvention comprises in the form shown, a rectangular support or base 12of some thickness which may constitute a block of electrical insulatormaterial. Block 12 constitutes the physical support means or substratefor the panel including, an outer clear glass envelope 14 which acts inthis case as a cover for base 12 and is hermetically sealed thereto,preferably about edge 16. While the envelope 14 may comprise clearglass, it is obvious that it may be formed of some other insulator,being at least translucent, so as to allow observation of a localizedarea of visible light output from the display panel 10.

The principal component of the panel comprises a thin electricalinsulator sheet 18 which may also be of glass, ceramic, etc. A first setof metal electrodes 20 are preferably first applied to the top of thesubstrate 12 by electrodeposition or any other conventional process, theelectrodes 20 being spaced from each other and parallel. In theillustrated embodiment there are approximately three lines per inch. Thethin insula tor l8 (soft glass, hard glass, ceramic) is applied on topof the substrate 12 overlying conductors 20 of a thickness typically inthe range of a micron to several mils. On the upper surface 22 of thethin insulator sheet 18 there is formed a second set of electrodes 24which are similarly formed, consisting of thin strips of metal which liepreferably orthogonal or approximately so to the underlying conductors20. As such, the upper and lower conductors or electrodes 24 and 20extend in crossed paths, spaced from each other by the thickness of theinsulator sheet 18. The hermetically sealed cover or envelope 14confines an inert gaseous atmosphere such as neon, indicated at 26, incontact with one surface 22 of the insulator sheet 18 carryingconductive electrodes 24.

The invention involves the phenomena of localized gas discharge whichtakes place on the surface of the insulator 18 creating localized areasof visible light output as identified at 28, in this case, on eitherside of the upper electrode 24. Alternating current voltage isselectively applied to the electrode by conventional switch means.However, to illustrate in the most simple manner the application of thesame, a source of alternating voltage (not shown) is connected toterminals 30 with lead 32 connecting one of the terminals 30 to aselected upper electrode 24 while lead 34 connects the other terminal 30to a selected underlying or bottom electrode 20. In the area of theintersection of these spaced electrodes, corona discharge occurs on theupper surface 22 of the insulator, that is, that surface which faces theinert gas atmosphere 26.

The crossed but spaced electrodes define individual gaseous displaycells and, in the illustrated embodiment, a matrix constituting threelines per inch has been successfully fired in a neon atmosphere of 200torr. With the application of an alternating current firing voltage ofabout 500 volts (peak-topeak), the device shown is bistable in a neonatmosphere of :10 percent nitrogen (at torr.). The upper set ofelectrodes 24 which are normally exposed to the inert gaseousatmosphere, may be protected by a thin layer 36 of electrical insulationmaterial which has the effect of slowing down the sputtering process andincreases the memory margin.

What is claimed is:

1. A gas discharge display panel comprising: an insulator substrate, afirst set of spaced parallel electrodes on one surface of saidsubstrate, a glass sheet overlying said first set of electrodes, asecond set of spaced electrodes carried on the outer surface of saidglass sheet orthogonally to said first set, a clear glass envelopeoverlying one surface of said sheet carrying said second electrode setand spaced therefrom, a confined neon atmosphere within the spacebetween the one surface and said clear glass envelope, and means forsupplying an alternating current voltage of sufficient magnitude acrossselected electrodes of each set to cause a discharge on the surface ofsaid glass sheet facing the gaseous atmosphere with calized visiblelight output in the crossing area of selected electrodes.

2. A display panel comprising:

an electrical insulator in the form of a thin sheet, means formaintaining an inert ionizable gas atmosphere on one side of said sheet,at least one conductor formed on said one side of said sheet, at leastone conductor formed on the side of said sheet opposite to said oneside, said two conductors partially overlapping to form a crossoverpoint, and means connected to said two conductors for applying apotential difference across said crossover point to cause a gasvdischarge in said inert ionizable gas atmosphere in the vicinity of thecrossover point.

3. The display panel of claim 2 further including a first plurality ofparallel conductors on said one side of said sheet and a secondplurality of parallel conductors on said opposite side, said secondplurality of conductors being orthogonal to said first plurality ofconductors, and means coupled to pairs of electrical conductorscomprising one conductor of said first plurality and one conductor ofsaid second plurality for selectively applying an alternating potentialdifference at the crosspoint of said conductor pairs.

4. The display panel as claimed in claim 3 wherein said thin insulatorsheet is supported by an electrical insulator block which underlies thesame and said inert gaseous atmosphere is confined to the displaysurface thereof by an overlying glass envelope hermetically sealed tosaid block.

5. The display panel of claim 3 further including an insulation layeroverlying and in contact with said first plurality of conductors.

6. In a gas discharge display device wherein a potential differenceapplied at selective locations across an ionizable gas atmosphereretained in a display panel causes selective discharges along with thegeneration of positive and negative charges tending to counteract thepotential difference and extinguish the discharge, subsequent reversalsof the potential difference causing successive pulsating discharges atthe selected locations, the improvement comprising:

a display panel including a dielectric sheet, one surface of which is incontact with said ionizable gas atmosphere;

a first plurality of conductors spaced along said one surface;

a second plurality of conductors spaced along a second surface of saiddielectric sheet parallel to said first surface, and remote from saidgas atmosphere, said second plurality of conductors at least partiallyoverlapping said first plurality of conductors to form a plurality ofcrossover points; and

means coupled to said first and second pluralities of conductors forselectively applying the potential difference across selectedcrosspoints to generate a discharge in the gas atmosphere in thevicinity of the selected crosspoints.

1. A gas discharge display panel comprising: an insulator substrate, afirst set of spaced parallel electrodes on one surface of saidsubstrate, a glass sheet overlying said first set of electrodes, asecond set of spaced electrodes carried on the outer surface of saidglass sheet orthogonally to said first set, a clear glass envelopeoverlying one surface of said sheet carrying said second electrode setand spaced therefrom, a confined neon atmosphere within the spacebetween the one surface and said clear glass envelope, and means forsupplying an alternating current voltage of sufficient magnitude acrossselected electrodes of each set to cause a discharge on the surface ofsaid glass sheet facing the gaseous atmosphere with localized visiblelight output in the crossing area of selected electrodes.
 2. A displaypanel comprising: an electrical insulator in the form of a thin sheet,means for maintaining an inert ionizable gas atmosphere on one side ofsaid sheet, at least one conductor formed on said one side of saidsheet, at least one conductor formed on the side of said sheet oppositeto said one side, said two conductors partially overlapping to form acrossover point, and means connected to said two conductors for applyinga potential difference across said crossover point to cause a gasdischarge in said inert ionizable gas atmosphere in the vicinity of thecrossover point.
 3. The display panel of claim 2 further including afirst plurality of parallel conductors on said one side of said sheetand a second plurality of parallel conductors on said opposite side,said second plurality of conductors being orthogonal to said firstplurality of conductors, and means coupled to pairs of electricalconductors comprising one conductor of said first plurality and oneconductor of said second plurality for selectively applying analternating potential difference at the crosspoint of said conductorpairs.
 4. The display panel as claimed in claim 3 wherein said thininsulator sheet is supported by an electrical insulator block whichunderlies the same and said inert gaseous atmosphere is confined to thedisplay surface thereof by an overlying glass envelope hermeticallysealed to said block.
 5. The display panel of claim 3 further includingan insulation layer overlying and in contact with said first pluralityof conductors.
 6. In a gas discharge display device wherein a potentialdifference applied at selective locations across an ionizable gasatmosphere retained in a display panel causes selective discharges alongwith the generation of positive and negative charges tending tocounteract the potential difference and extinguish the discharge,subsequent reversals of the potential difference causing successivepulsating discharges at the selected locations, the improvementcomprising: a display panel including a dielectric sheet, one surface ofwhich is in contact with said ionizable gas atmosphere; a firstplurality of conductors spaced along said one surface; a secondplurality of conductors spaced along a second surface of said dielectricsheet parallel to said first surface, and remote from said gasatmosphere, said second plurality of conductors at least partiallyoverlapping said first plurality of conductors to form a plurality ofcrossover points; and means coupled to said first and second pluralitiesof conductors for selectively applying the potential difference acrossselected crosspoints to generate a discharge in the gas atmosphere inthe vicinity of the selected crosspoints.